TM 55-2210-223-34TO 45A2-2-14-223-44. AIR COMPRESSOR ASSEMBLY (cont)TESTCAUTIONWhen performing orifice test, check that oil pressure is never less than 15 psi (103 kPa). Damage to aircompressor can result.20. Perform an orifice test by the following:a.Connect an orifice holder with 17/64-inch (6.7 mm) orifice in air reservoir drain cock. Use orifice with squareedges bored through plate 1/16 inch (1.6 mm) thick.b. Start engine and run until it is at normal operating temperature.c. Close outlet valve from reservoirs, open drain cock, and leave open for all tests.d. Run air compressor at least 2 minutes at low speed (table 3-4) and take a pressure reading. Record aircompressor speed (rpm) and corresponding pressure.e. Run air compressor at least 2 minutes at high speed (table 3-4) and take a pressure reading. Record aircompressor speed (rpm) and corresponding pressure.f. Run air compressor 15 minutes (drain cock open) and repeat steps d and e.g. Use table 3-5 and compare speed-pressure readings.h. Safety valve and check that intercooler safety valve opens at 60 psi (414 kPa). Replace damaged intercoolersafety valve.21.Apply air to unloading valves and check that unloading valves open at 130 psi (896 kPa) and close at 140 psi (965kPa). If unloading valves do not open and close at specified psi, refer to paragraph 3-45 and adjust air compressorgovernor.22.Apply air pressure to main reservoir safety valve and check that main reservoir safety valve opens at 150 psi (1034kPa). Adjust main reservoir safety valve by turning regulating nut. Replace damaged main reservoir safety valve.3-174